In a so-called metal coil material processing line that includes a slitter line for a coiled long metal material, a tension device before winding after slitting is disposed therein. Examples of this tension device include a roll bridle, a belt-type tension device, and the like.
This tension device imparts a coiling tension before a winder to slit band sheets so that the band sheets are tightly and securely wound around a winding coil.
In addition, as the tension device, there is a coiling tension applying device of a multi-belt type tension system (refer to Patent Documents 1, 2, and 3) in which a metal band sheet is clamped from above and below the metal band sheet by a plurality of divided endless belts to impart a coiling tension by a frictional force of the backside of the belt.
In the device of this multi-belt type tension system, since the inside and outside of the belt have different coefficients of friction, uniform tension can be imparted to each band sheet. In addition, since the belt surface and the band sheet are rotated without sliding, scratches are not easily generated on the surface of the band sheet.
For example, Patent Document 1 discloses a coiling tension applying device 100 shown in FIG. 10A. In the device 100, a belt 102 is stretched by a pair of pulleys 101, and the belt 102 is pressed by a pushing plate 104 interlocked with a cylinder 103. Further, the plurality of pulleys 101 is provided side by side, and a plurality of belts 102 is stretched.
In the device 100, the pulley 101, the belt 102, and the pushing plate 104 are integrated and arranged so as to face each other vertically. Between the belts 102 facing each other, the slit band sheet 106 is conveyed to a winder which is not shown, and the belt 102 vertically compresses the band sheet 106 via the upper and lower pushing plates 104.
In addition, in the belt 102, the outer side of the belt is made of a material having a large coefficient of friction and the inner side of the belt is made of a material having a small coefficient of friction. When the band sheet 106 is brought into contact with the outer surface of the belt 102, the coefficient of friction on the outer side of the belt is large, so that when winding of the band sheet is started by the winder, the belt 102 moves with the band sheet 106 without slipping.
The pulley 101 is axially supported to be freely rotatable and the belt 102 is circulated. Between the inner surface of the belt 102 and the pushing plate 104, a coefficient of friction of the inner surface of the belt is small, so that slippage occurs and coiling tension in a direction opposite a conveying direction is applied to the band sheet 106 by the frictional force generated at the same time. Similarly, a device described in Patent Document 2 has a structure using a plurality of pulleys.
Patent Document 3 discloses a tension applying device 200 shown in FIG. 10B. The device 200 has a pressure applying body 202 that allows a belt 201 to be stretched on an outer peripheral surface thereof. The pressure applying body 202 includes two belt reversing portions 203 each having a cross section which is formed in an arc shape and a pressing portion 204 which presses the inner surface of the belt 201.
Protrusions are provided at regular intervals on the outer peripheral surface of the pressure applying body 202, and a plurality of belts 201 is stretched side by side. In the device 200, the pressure applying bodies 202 are arranged to face each other vertically. When a band sheet 205 which has been slit is conveyed to a winder between the facing belts 201, the belt 201 vertically compresses the band sheet 205 via the upper and lower pressing portions 204.
In addition, in the belt 201, the outer side of the belt is made of a material having a large coefficient of friction and the inner side of the belt is made of a material having a small coefficient of friction, in the same manner as in the device 100 of Patent Document 1. The belt 201 in contact with the band sheet 205 is circulated, and coiling tension is generated on the belt 201 in the same manner.